In the expansion, many new features were added to make Muslims more interesting:

Decadence - This increases as you have more unlanded males in your family. High decadence leads to big problems for your nation, such as Tribal Invasions and weaker levies. To solve this penalty, the player must imprison, execute or assassinate male relatives; Muslim characters gain no tyranny from imprisoning brothers. Once decadence reaches high levels, a tribe of "desert warriors" spawn to take over the decadent dynasty's realm.

Laws - Laws now cost Piety to change as a Muslim. In addition, Muslim characters are unable to change succession and gender laws.

Agnatic Open succession - a Muslim's most powerful son will take over for him. This comes at a cost of being locked into this succession law, however.

Polygamy - Muslims may have up to four wives. A Muslim is expected to have one extra wife per level of title, starting at the count level, and capped at the king level. Having less than the expected results in a monthly prestige drop while having more than the expected is a prestige gain. This gives off huge amount of sons, which in-turn multiply, causing huge amounts of decadence if not imprisoned or assassinated.

Muslim Invasion CB. All Muslims can conquer a single province at the cost of piety. In addition, Muslims are capable of declaring war on any Muslims not of their exact branch of Islam (if the target is not in a holy war with infidels). Caliphs may subjugate any de-jure Muslim kingdom.

100+ new Muslim specific in-game events, such as problems in the Harem, Shia vs Sunni tensions and making the Hajj